As the size of chips increases, the problem of differences in thermal expansion between a semiconductor chip, for example, made of monocrystalline silicon, and a superordinate circuit board or a rewiring plate, for example, made of glass-fiber-reinforced epoxy resin, becomes more significant. Thus, in the case of the connecting elements used hitherto, such as, for example, flip-chip contacts, which have external contact balls or external contact bumps made of a solder alloy, there is the risk that sheer stresses on solder balls or solder bumps that are a few micrometers in size can no longer be reduced by plastic creepage or by plastic deformation. The consequence is that the connecting elements exhibit a tear-off risk that increases as the chip size increases. This tear-off risk can be alleviated in part by suitable plastics, which are also called “underfill,” supporting the connecting elements, in particular, the flip-chip contacts, but this is associated with an increased production outlay.
Other solutions to the problem envisage using elastic external contacts having a rubber-elastic core and a metallic conductor track that nestles against the core. In this case, the metallic conductor track is not self-supporting, but rather relies on support from the rubber-elastic core, which is associated with an increased production costs for elastic connecting elements of this type.
A further solution, known as “microspring,” provides wire-bonded, resilient metal wire constructions as connecting elements in order to enable the compensation in the coefficients of thermal expansion of, for example, silicon and epoxy resin. This solution also has low mechanical stability due to the bonding wires used, so that mechanical protection is required which increases the production costs for “microsprings” of this type, and thus the production costs, in particular, as a result of the serial production of the wire-bonded connecting elements.
To enable an elastic, compliant connection between contact areas of a semiconductor chip or of a semiconductor wafer and contact pads of a superordinate circuit board and reduce the tear-off risk of connecting elements is desirable.